The present invention relates to a liquid level detecting apparatus capable of detecting a liquid height inside a fuel tank etc. of an automobile, and particularly to an assembly structure of a slider used in the liquid level detecting apparatus and the liquid level detecting apparatus using this assembly structure.
A liquid level detecting apparatus constructed so that a float moves up and down according to a liquid level and thereby an electrical contact point moves while sliding on a resistance plate and thereby the liquid level is converted into a potential difference and a liquid height can be detected has been known conventionally as the liquid level detecting apparatus for detecting the height of liquid used as fuel of the inside of a fuel tank of an automobile (for example, Patent Document 1).
A liquid level detecting apparatus 100 described in this Patent Document 1 is an apparatus for detecting a liquid height of the inside of a fuel tank of an automobile etc., and includes a float 101 for moving up and down according to displacement of a liquid level to be measured, a float arm 102, a resistance plate 103 and a slider 104, and the float 101 floating on the level of liquid used as fuel F inside the fuel tank is attached to the top of the float arm 102 as shown in FIGS. 7 and 8.
In FIG. 7, the float arm 102 in which the proximal end side is bent in a vertical direction orthogonal to a paper surface is rotatably supported in a bearing part 110 (see FIG. 8B) in which the proximal end of the float arm 102 is disposed in a frame 105 through the slider 104. Also, the resistance plate 103 and further the slider 104 which includes a conductive slide arm (corresponding to a contact or a contact point spring) 108 and an arm holder 106 integrally assembling this slide arm 108 and slides on the resistance plate 103 in conjunction with rotation of the float arm 102 are attached to the frame 105. In addition, in the drawings, numeral 107 shows a conductive pattern and numeral 109 shows a contact point disposed in the slide arm 108.
Such a liquid level detecting apparatus 100 is constructed so as to perform electrical continuity between the resistance plate 103 and the slide arm 108 assembled in the arm holder 106. And the arm holder 106 turns according to the liquid level L to be detected and a position relative to the resistance plate 103 varies, so that the liquid level L is detected using variations in a resistance value between the resistance plate 103 and the slide arm 108.
Incidentally, an operation of contact between the resistance plate 103 and the slide arm 108 assembled in the arm holder 106 depends on elastic deflection of the slide arm 108, so that a resistance value to be detected cannot be detected accurately when the deflection of the slide arm 108 varies. Hence, for example, by performing insert molding of the slide arm 108 in the case of molding the arm holder 106, the slide arm 108 is integrated with the arm holder 106 and the variations are eliminated.
[Patent Document 1] Japanese Patent Publication Number 2009-8535
However, in such insert molding, workability is bad and cost increases. Hence, the insert molding is avoided and, for example, a method for disposing a caulked part in a fixed surface of the arm holder 106 and caulking the slide arm is also examined. However, in such a method depending on only the caulking, strength of the caulked part may reduce gradually due to deterioration etc. associated with long-term use.